Changed ambiguous CONFGEN filename

Changed ambiguous CONFGEN filename

CONFGEN message included the name of the stamp file without the
extension. This was ambiguous because in the case of named (not
LOCAL_CONFIG_H) config files, the final header file is located in
different directory than stamp file and therefore the message mentioned
a non-existent file path. Now, the CONFGEN message only includes
filename without directory. The full path is shown in update message.